On the basis of the large change in electrophoretic mobility of DNA in polyacrylamide gels when denaturation occurs, a large number of DNA molecules can be characterized independently. Combination of this property with electrophoretic separation on the basis of size will be developed to achieve precise, comprehensive, proximate analysis of restriction enzyme products of bacterial DNA as a step toward the same goal with eukaryotic DNA. Progress will be assessed by the capacity to recognize distinct genetic differences among bacterial strains and the presence of an integrated phage genome. BIBLIOGRAPHIC REFERENCES: L.S. Lerman, L.S. Wilkerson, J.H. Venable, Jr. and B.H. Robinson "DNA Packing in Single Crystals Inferred from Freeze-Fracture-Etch Replicas". J. Mol. Biol. 108: 271, 293, 1976.